A small, irregular moon with a bright, water-ice-rich surface and chaotic rotation.
Nix is one of Pluto’s four small outer moons. It was discovered in 2005 with the Hubble Space Telescope during a search for additional members of the Pluto system. Nix orbits between Styx and Kerberos.
Unlike Charon, Nix is not tidally locked. Hubble observations and dynamical models show that it tumbles chaotically in the changing gravitational field of the Pluto–Charon pair.
New Horizons showed Nix to be highly reflective and irregular in shape. Enhanced-color images revealed a reddish region associated with a large crater, and later spectral observations provided strong evidence that its surface is covered largely by water ice.
NASA’s Eyes on the Solar System places Pluto in its wider solar system setting and lets you examine the Pluto–Charon system in three dimensions. Rotate the view, zoom in or out, and use the time controls to follow the modeled motion of the system.
NASA Eyes is an interactive visualization provided by NASA/JPL and loads from eyes.nasa.gov. If the embedded view is unavailable, use the full-screen link above.
Pluto has five known moons. Charon is by far the largest and forms a closely coupled pair with Pluto. Farther out, the four much smaller moons—Styx, Nix, Kerberos and Hydra—follow nearly circular orbits around the Pluto–Charon system.
Diagram is schematic; sizes and orbital distances are not to scale.
NASA Science provides mission background, observations and image collections; Wikipedia offers a broader reference overview with citations.
